adds tests

bind.go

@@ -62,12 +62,19 @@ func BindContext[A, B any](scope Scope, input Incr[A], fn BindContextFunc[A, B])
 		parents: []INode{bindLeftChange},
 	})
 	bind.main = bindMain
+
 	// propagate errors to main from the left change node
 	bindLeftChange.n.onErrorHandlers = append(bindLeftChange.n.onErrorHandlers, func(ctx context.Context, err error) {
 		for _, eh := range bindMain.n.onErrorHandlers {
 			eh(ctx, err)
 		}
 	})
+	// propagate aborted events to main from the left change node
+	bindLeftChange.n.onAbortedHandlers = append(bindLeftChange.n.onAbortedHandlers, func(ctx context.Context, err error) {
+		for _, eh := range bindMain.n.onAbortedHandlers {
+			eh(ctx, err)
+		}
+	})
 	return bindMain
 }
 

bind_test.go

@@ -1179,7 +1179,6 @@ func Test_Bind_cycle(t *testing.T) {
 	nodesThatErrored := make(map[Identifier]INode)
 
 	var b1 BindIncr[string]
-
 	b0v := Var(g, "a")
 	b0v.Node().OnError(func(_ context.Context, err error) {
 		nodesThatErrored[b0v.Node().id] = b0v
@@ -1199,10 +1198,7 @@ func Test_Bind_cycle(t *testing.T) {
 		nodesThatErrored[b1v.Node().id] = b1v
 	})
 	b1 = Bind(g, b1v, func(bs Scope, which string) Incr[string] {
-		if which == "a" {
-			return b0
-		}
-		return Return(bs, "bar")
+		return b0
 	})
 	b1.Node().OnError(func(_ context.Context, err error) {
 		nodesThatErrored[b1.Node().id] = b1
@@ -1288,3 +1284,69 @@ func Test_bindLeftChange_RightScopeNodes(t *testing.T) {
 
 	testutil.Equal(t, 2, len(bindTyped.bind.lhsChange.RightScopeNodes()))
 }
+
+func Test_Bind_aborted(t *testing.T) {
+	ctx := testContext()
+	g := New(
+		OptGraphClearRecomputeHeapOnError(true),
+	)
+	nodesThatErrored := make(map[Identifier]INode)
+	nodesThatAborted := make(map[Identifier]INode)
+
+	hookNode := func(n INode) {
+		n.Node().OnError(func(_ context.Context, _ error) {
+			nodesThatErrored[n.Node().id] = n
+		})
+		n.Node().OnAborted(func(_ context.Context, _ error) {
+			nodesThatAborted[n.Node().id] = n
+		})
+	}
+
+	var b1, b2 BindIncr[string]
+	b0v := Var(g, "a")
+	hookNode(b0v)
+	b0 := Bind(g, b0v, func(bs Scope, which string) Incr[string] {
+		if which == "a" {
+			return Return(bs, "foo")
+		}
+		return b1
+	})
+	hookNode(b0)
+
+	b1v := Var(g, "a")
+	hookNode(b1v)
+	b1 = Bind(g, b1v, func(bs Scope, which string) Incr[string] {
+		return b2
+	})
+	hookNode(b1)
+
+	b2v := Var(g, "a")
+	hookNode(b2v)
+	b2 = Bind(g, b2v, func(bs Scope, which string) Incr[string] {
+		return b0
+	})
+	hookNode(b2)
+
+	o := MustObserve(g, b2)
+	hookNode(o)
+
+	err := g.Stabilize(ctx)
+	testutil.NoError(t, err)
+	testutil.Equal(t, "foo", o.Value())
+
+	b0v.Set("b")
+
+	err = g.Stabilize(ctx)
+	testutil.Error(t, err)
+	testutil.Equal(t, "foo", o.Value())
+
+	testutil.Equal(t, 1, len(nodesThatErrored))
+	_, ok := nodesThatErrored[b1.Node().id]
+	testutil.Equal(t, true, ok)
+
+	testutil.Equal(t, 2, len(nodesThatAborted))
+	_, ok = nodesThatAborted[b0.Node().id]
+	testutil.Equal(t, true, ok)
+	_, ok = nodesThatAborted[b1.Node().id]
+	testutil.Equal(t, true, ok)
+}

graph.go

@@ -106,7 +106,10 @@ func OptGraphPreallocateSentinelsSize(size int) func(*GraphOptions) {
 // OptGraphClearRecomputeHeapOnError controls a setting for whether or not the
 // recompute heap is cleared of nodes on stabilization error.
 //
-// If not provided, the default is to not clear the recompute heap, but leave nodes in place.
+// By default the graph will not clear the recompute heap, and instead leave nodes in place.
+//
+// If this option is provided, and `shouldClear` is `true`, then the recompute heap
+// will be cleared on error, and the `OnAborted` handlers of nodes will be called.
 func OptGraphClearRecomputeHeapOnError(shouldClear bool) func(*GraphOptions) {
 	return func(g *GraphOptions) {
 		g.ClearRecomputeHeapOnError = shouldClear

recompute_heap.go

@@ -24,8 +24,8 @@ func (rh *recomputeHeap) clear() (aborted []INode) {
 	defer rh.mu.Unlock()
 
 	var next INode
+	aborted = make([]INode, 0, rh.numItems)
 	for rh.numItems > 0 {
-		aborted = make([]INode, 0, rh.numItems)
 		next, _ = rh.removeMinUnsafe()
 		next.Node().heightInRecomputeHeap = HeightUnset
 		aborted = append(aborted, next)